1. Field of the Invention
The field of the present invention relates to portable data entry and storage devices. In particular, the invention relates to pen-based devices that produce, recognize and store handwriting.
2. Background
In recent years, many products have been developed that attempt to feature the simplicity and ease of a pen and paper at recording information while enabling the ready transfer of such information to computers and other information systems. Very often people initially commit their thoughts to paper only to find themselves having to reenter the information into a computer or other electronic device. One development effort that in part seeks to eliminate the task of retyping is the development and commercialization of character recognition (both optical and non-optical) software. Such software was developed to bridge the gap between the handwritten word on paper and the computer-readable and transferable representation of the word. While many such packages have been successfully commercialized, they also have inherent limitations. First, to use character recognition software, a page scanning system must initially capture information on a page. Thus, a scanning element is necessary to enable the character recognition software to perform its function. Second, the combination of the character recognition software and the page-scanning system become new elements that are added to the information transfer process. That is, they do not replace the pen and paper, but instead, introduce new task elements that replace rather than eliminate the task of reentering information.
On another front, portable digital assistants (PDAs) such as the Palm V™ by 3Com, Inc. have been commercialized in attempt to replace the need for pen and paper and eliminate the need to reenter information. However, when compared to pen and paper in terms of the ease with which to record information, they too are often impractical. While such devices have continually improved in terms of flexibility and performance, they remain relatively inflexible and limited in terms of the manner and type of information that can be entered and recorded. A structured writing style is often required that can reduce writing speed. Further, PDAs are bulkier than pens in that an electronic writing template is a necessary part of the device. Also, PDAs require a measure of training of the user to be useful. Thus, in these systems, to capably record information in a computer-readable format, much of the flexibility and ease of writing on paper by hand is sacrificed.
However, recently, numerous devices and systems have been described that claim to provide the recordation flexibility of pen and paper with the capability of storage in a computer-readable format. These devices are or use pen-like devices that, in real-time, store as computer-readable data, information as it is written on a paper medium.
Examples of such a device are disclosed in U.S. Pat. No. 5,774,602 issued to Taguchi et al. (“the '602 patent”) which is incorporated herein by reference. The '602 patent describes a writing device that uses a CCD detector to sense the handwriting written using the device. The device includes a microprocessor for converting the sensor's output into image data, a storage device for storing the image data, an output for downloading the image data, a stress sensor and a power supply. Similarly, U.S. Pat. No. 5,294,792 issued to Lewis et al. (“the 792 patent”) and incorporated herein by reference, describes a self-contained pen-computer that acquires data representative of written strokes of a stylus of a pen and then recognizes the symbols associated with the pen strokes. The recognized symbols are stored in a memory contained in the pen and are transmitted to a host computer using a transmitter integrated into the pen.
The devices disclosed in the '602 and '792 patents and others previously developed in the field of pen-based handwriting storage suffer from certain serious drawbacks. First, while many of the disclosed devices allow for initial training of a device before use to enhance the recognition performance for a specific user, the devices disclosed are limited to a particular writing regimen or style once use commences. After they are configured to a certain user, even the trainable devices such as the device disclosed in the '792 patent, require that the specific user maintain a specific writing style that a device is designed to recognize. If the user deviates from the device's operational requirements, the device's performance markedly drops. Thus, a need exists for a device that is not constrained to a particular writing style or writing structure.
As another drawback, the highest performance character recognition devices, including many PDAs, tend to require user-specific training to achieve their recognition performance levels. By tailoring each device to a particular user, the portability or transferability of any given device becomes greatly limited because the performance degrades rapidly as the use migrates from the use the device was trained to recognize. Thus, a need further exists for a device the performance of which is not limited to a narrow recognition scheme that restricts its portability between users.
Further, the devices disclosed in the prior art such as those in the '602 and '792 patents, invite a host of undesirable consequences because of the design philosophy that they adopt in performing character recognition. By recognizing text on a character-by-character basis, the devices described demand additional, larger, and/or higher power-consuming components. In the context of a pen-based real-time handwriting recognition system, such demands are completely inapposite to the inherent limitations of a pen-like device. The enormous variability in the handwritten representation of any given character requires that a device that adequately performs recognition on a character level have a significant processing and character reference storage capability. Such demands readily lead to implementations that compromise the need for such devices to be low power and of a size and shape that is not far removed from the conventional ball-point pen. Thus, a need exists for a device that employs a character recognition methodology that meets the practical constraints inherent in a viable pen-based handwritten character recognition and storage device.